Fluid dispensing system

ABSTRACT

For delivery of cleansing liquid to printing rollers, a collapsible chamber is incompletely filled with a liquid which is thereafter delivered directly to spray nozzles by compression of the chamber. Reexpansion of the chamber draws in a new charge of liquid and concurrently withdraws residual liquid from the spray orifices to prevent dripping on the cleaned printing rollers. A two chamber system is disclosed in which a new charge of cleaning liquid is received in and metered by a first chamber for subsequent transfer to the second chamber.

United States Patent [1 1 Brym [ Oct. 21, 1975 [54] FLUID DISPENSINGSYSTEM [75] Inventor:

[73] Assignee: Baldwin-Gegenheimer Corporation,

Stamford, Conn.

22 Filed: Feb.1l, 1974 [21] Appl. No.: 441,101

Stanley J. Brym, Torrington, Conn.

3,806,084 4/1974 Seese 222/571 X Primary Examiner-Robert B. ReevesAssistant ExaminerLarry H. Martin Attorney, Agent, or FirmSt. OngeMayers Steward &

Reens [57] ABSTRACT For delivery of cleansing liquid to printingrollers, a collapsible chamber is incompletely filled with a liquidwhich is thereafter delivered directly to spray nozzles by compressionof the chamber. Reexpansion of the chamber draws in a new charge ofliquid and concurrently withdraws residual liquid from the sprayorifices to prevent dripping on the cleaned printing rollers. A twochamber system is disclosed in which a new charge of cleaning liquid isreceived in and metered by a first chamber for subsequent transfer tothe second chamber.

7 Claims, 3 Drawing Figures US. Patent Oct. 21, 1975 Sheet10f2 3,913,797

US. Patent Oct.21,1975 Sheet 2 of2 3,913,797

Q3 Q? Q E. $8

1 mun DISPENSING svs'rsm BACKGROUND OF THE INVENTION AND SUMMARY Thisinvention relates to a fluid dispensing system and more particularly toliquid dispensing apparatus which is especially adapted for use as acleansing accessory for the ink-bearing rolls of a printing press.

A general approach to the intermittent cleaning of printing rollers isdescribed in US. Pat. No. 2,970,541, issued Feb. 7, l96l in the name ofHarold W. Gegenheimer. This patent discusses, for example, spraying aliquid solvent on the rollers to be cleaned, and following this byapplication of a wiping blade to the roller surfaces to remove thedissolved ink and the residual solvent. In further developments of thisprocedure, use has been made of a fixed array of spray noules forconveniently applying solvent to an extended area of the printing rollerdesired to be treated at a given time. This otherwise desirable andconvenient approach has, however, introduced the possibility of unwanteddripping of residual solvent retained in the spray nozzles after thewiping phase of the cleansing operation has been completed. Suchdripping, when it occurs, may deposit pools of solvent on the ostensiblyclean roller surfaces, with resulting harmful effects on subsequentprinting operations.

It has been recognized that one cure for this problem lies in positivelyterminating the supply of solvent to the spray nozzle orifices at theend of the spraying cycle. Specific means to this end have beendescribed in US. Pat. No. 3,508,711, issued Apr. 28, i970 in the name ofT. G. Switall. The means proposed by this patent comprise a set ofspring-seated needle valves, each member of the set being associatedwith a specific spray nozzle and being closed except in the presence ofpressurized solvent in the solvent supply line which connects with thenozzle assembly. Solvent pressure in the supply line is in turncontrolled by an appropriate valving system. Thus, one specificallydescribed control arrangement comprises an air-actuated bellows which inthe air-on condition channels pressurized solvent to the nozzle valves,forcing them open, and which, in the air-off" condition, terminates theflow of solvent and at the same time relieves pressure in the nozzlesupply line sufficiently to permit the individual nozzle valves toclose.

While the system just described affirmatively prevents any substantialcontinuing leakage of solvent from the various nozzles, it does notpreclude single droplets from being formed by the small residue ofsolvent which may be retained at each nozzle opening even afier thesupply of solvent is terminated. Because even a single such droplet,falling on a critical area of a printing roller, may produce a printingdefect, still further safeguarding measures are found desirable.

The present invention solves this residual problem by providing means bywhich, at the end of each solvent supplying cycle, a negative pressure"is developed at the supply line side of each spraying orifice, thusdrawing back into the orifice (and eventually into the supply line) anylingering quantities of solvent which may occupy or surround the orificeopening. In a preferred embodiment of the invention this result isaccomplished by the provision of a fluid dispensing system in which boththe positive pressure needed to accomplish spraying action and thenegative pressure needed to draw back into the system residual orificedroplets are produced directly by on-off control of a supply ofpressurized solvent.

DETAILED DESCRIPTION Further and more detailed aspects of the inventionwill be made apparent by reference to the following specification takenin connection with the appended drawings.

In the drawings:

FIG. 1 is a view, partly in true cross-section and partly schematic, ofa fluid dispensing system in accordance with the invention;

FIG. 2 is a sectional view of the principal functional elements of FIG.1 shown in an altered operating condition; and

FIG. 3 is a schematic representation of an exemplary control circuit foruse with the system of FIG. 1.

In FIG. 1 there is shown schematically a liquid dispensing system whichcomprises a source 10 of pressurized liquid and, at the right hand endof the Figure, an outlet nozzle 15 having an orifice through whichliquid from the source is desired to be projected in a controllablefashion. In the printing press application with which the invention isprincipally concerned the liquid source 10 may comprise a tank ofcleansing solvent (for example, a petrochemical derivative) which ismaintained under pressure as by a compressed air source (not shown)associated with the tank. In the same application, the nozzle 15 may beone of several similar nozzles connecting with a manifold 17. Thismanifold, which is shown in section, may be assumed to have considerableextension in its axial direction and to carry along its length of seriesof spaced nozzles corresponding in form and function to the nozzle 15.

In proximity to the nozzle 15 there is shown in end view a segment 20 ofwhat may be taken to be an inking roller. As will be readily understood,such a roller in its normal usage tends to acquire surface accumulationsof ink which must be removed from time to time by a cleansing operation.In this context it is the function of the nozzle 15 (and of the similaradditional nozzles associated with the manifold 17) to spray a cleansingsolvent on the roller surface at times and during periods which may beselected by the operator of the printing equipment. In connection withthe roller 20 there is further shown a wiping blade 25 which, under thecontrol of the equipment operator, may be moved into contact with thesurface of the roller in order to scrape from it the mixture of solventand dissolved ink which results from a spraying operation. The removedsubstances are collected in a trough 27 from which they may be disposedof by any suitable means. A complete roller cleaning system employingcleaning elements such as those just referred to is fully disclosed inUS. Pat. No. 2,970,541, previously referred to herein and herebyincorporated by reference in the present specification.

As has been indicated, spraying and wiping procedures are now widelyused in the printing art. As has been further stated, however, theseprocedures introduce the problem of after-cleansing drippage of solventfrom spray nozzles as heretofore employed, with resultant harmfuleffects in subsequent printing operations. The aspects of FIG. 1 whichhave not so far been described a new form Of flow control apparatuswhich is to be interposed in the conduit system extending between thesource and the spray orifice a for controlling the fiow of liquidthrough the conduit system in a fashion which will eliminate thedrippage difficulty just referred to.

In general terms, the flow control apparatus employed by the presentinvention comprises the combination of means for alternativelyestablishing fiow of liquid from the source 10 to a conduit portion 30which connects with the manifold 17 and through the manifold with thenozzle 15 and secondly, under control of an appropriate cycling device,interrupting such flow after a desired time interval. With the meansjust described there is combined further means, effective uponinterruption of liquid flow to the manifold 17 to establish a negativepressure within the conduit portion 30 thereby to withdraw residualliquid from the orifice of the spray nozzle 15. (The term negativepressure is here used in the broadest sense to mean not only a pressurewhich is sufficiently below atmospheric pressure to produce in-draft ofair through the nozzle orifice but also any pressure which is reducedsufficiently below a pre-existing pressure to induce or permit positiveinflow of fluid through the spray orifice whether under the influence ofair pressure, gravity or otherwise).

In the specific embodiment which is illustrated in FIG. 1, the controlmeans described generally in the preceding paragraph comprises a coupledpiston as sembly designated generally by the numeral 35. This assemblyis shown in longitudinal cross-section, but as seen end-on, would appearas of generally cylindrical configuration. Thus, it includes disk-likeend plates 37 and 38 which are joined by a set of symmetrically disposedtie rods 40, of which only two are shown. Compressively retained betweenthe end plates in end-toend relation are a first cylinder 42 and asecond cylinder 44, the latter being of significantly larger diameterthan the former. The cylinders 42 and 44 are separated at their mostnearly abutting extremities by a circular plate 46 upon which eachcylinder bears circularly as indicated at 48 and 50, respectively.Centrally disposed within the cylinder 42 there is a smallerpiston-forming cylinder 52 which terminates at its left hand in acircular cylinder head 54. Extending across the outer surface of thecylinder head is flexible roll-up diaphragm 56 which may consist offabric having a solventresistant impregnation and the function of whichwill be further described at a later point. In the illustrated positionof the piston cylinder 52 the diaphragm S6 extends across the head ofthe piston then loops back upon itself in the annular space providedbetween the cylinders 42 and 52 as indicated at 56a. It terminatesperipherally in an enlarged bead 56b which is compressively retainedbetween the end plate 37 and an annular ring 58 which also provides acentering retaining means for the cylinder 42. A circular cover plate 60which has a screw threaded attachment 62 to other parts of the pistonstructure compressively engages the central area of the diaphragm 56,holding it firmly against the outer surface of the cylinder head 54. Aswill appear at a later point, the space between the end plate 37 and thefacing surface of the diaphragm 56 provides a collapsible (andextensible) chamber, the volume of which may be varied by movement ofthe piston cylinder 52 for purposes subsequently to be described.

Extending axially of the piston cylinder 52 is a connecting rod 65 whichis secured to the cylinder end wall 54 by means of the threaded screw62. This connecting rod extends through the dividing wall 46, beingslidably supported in the central portion of that wall by means of abushing 70. To the right of the wall 46 the connecting rod occupies anaxial position within a second piston cylinder 75, which is terminatedat its right hand end by a cylinder head held in place by attachment tothe abutting extremity of the connecting rod 65. Attached to the outersurface of the cylinder head is a flexible roll-up diaphragm 83 which inturn is clamped against the cylinder head by a circular cover plate 84held in place by the screw threaded member 86. The diaphragm 83 issimilar in construction to the diaphragm 56, previously described, and,like that diaphragm, terminates at its peripheral edge in an enlargedbeaded portion 83b. As shown, this beaded portion is held against thecircular end wall 38 by a grooved clamping ring 90. The entire structureas so far described is held in demountable assembly by the tie rods 40,previously referred to.

In considering the operation of the control apparatus, it needs to benoted that the end plate 37 has an inletoutlet port by which liquid maybe admitted to and withdrawn from the otherwise generally sealed spacebounded by the flexible diaphragm 56. Similarly, the opposite end wall38 has an inlet-outlet port 99 by which liquid may be admitted to andwithdrawn from the space bounded by the second diaphragm 83. It is alsoimportant at this point to note that the volumetric space containedwithin the diaphragm 83 in the fully expanded condition in which it isshown in FIG. 1, significantly exceeds the corresponding volumetricspace within the diaphragm 56 in the fully expanded condition in whichit is shown in FIG. 2. The latter observation makes it appropriate toconsider next the operational steps and the practical results (in termsof utility of the invention) which are involved in changing theapparatus from the condition shown in FIG. 1 to that shown in FIG. 2. Inthis connection attention is first directed to the two-position slidevalve illustrated schematically in both FIGS. 1 and 2. This is shown(again schematically) as comprising an outer sleeve 1100 within which isslidably mounted a twochambered, closed-end cylinder 11%. For convenientsubsequent reference the two chambers of the cylinder are separatelylabelled A and B. It will be seen that in the position of the cylinder11% which is represented in FIG. I, passage of liquid from thepressurized liquid source 10 is effectively blocked. In thiscircumstance, however, chamber B provides a connection between the port95 which communicates with the interior of diaphragm 56 and port 99which communicates with the interior of diaphragm 83. This connection iscreated by a conduit system which includes a tubular connectionextending between the port 95 to a port 122 in valve chamber B, thencethrough port 124 in valve chamber B to a further tubulation 126 whichconnects at its opposite extremity 126a with port 99 formed in end wall38. It needs to be observed at this point for further reference at alater stage that the tubulation 126 also has a direct connection throughthe branch tubulation 30 with the mainfold 17 and through this andthrough the connecting nozzle 15 with the orifice 15a out of whichsolvent liquid is eventually to be projected.

Let it now be assumed that by means to be explained at a later point aquantity of solvent liquid has previously been introduced into the spacewithin the diaphragm 83 as indicated at 130. Note also at this pointthat the two-chambered valve cylinder 110b is movable axially under thejoint control of a tension spring 135 and a solenoid showndiagrammatically as comprising a magnetic core or plunger 138 and anenergizing coil 139. In the condition of the apparatus illustrated inFIG. I, solenoid coil 139 assumed to be de-energized, but it is furtherassumed that its terminals 140 are connected to a source of possibleenergization (see FIG. 3). Under these circumstances if energization isnow applied to the terminals 140, the valve cylinder ll0b will be drawnto the right by the solenoid, as shown in FIG. 2, and the ports 145 and146 of valve chamber A will establish direct connection betweentubulation a leading from the pressurized liquid source 10 andtubulation 120 leading to the port 95 which communicates with theinterior of the diaphragm 56. At the same time the left hand end of thetubulation 126 will be cut off from communication with tubulation 120.In these circumstances, pressurized liquid will enter the space boundedby the diaphragm 56 and, in due course, will move the piston cylinder 52into the position which it is shown to occupy in FIG. 2. In so doing itwill, among other things, overcome the opposing force of compressionspring 150 and will cause that spring to store potential energy forperformance of a further function to be described at a later point.Because compression of the spring 150 tends to produce an objectionabletwisting motion of the parts with which the spring is associated(necessarily including the diaphragm 56), the right hand end of thespring is provided with an antifriction thrust bearing assembly 155which permits that end of the spring to rotate freely, thus eliminatingthe application of torsional force to the diaphragm. Secondly, righthand motion of the piston cylinder 52 will produce corresponding motionof the connecting rod 65 and identical motion of the piston cylinder 75and the associated cylinder head 80. As suggested by FIG. 2, this willproduce compression of the space within the diaphragm 83, the degree ofcompression being determined by the location of the abutment 160, whichmay be made adjustable as shown to accommodate differing circumstancesof operation. Attention is directed to the fact that air holes 165formed in the dividing plate 46 prevent entrapment of air in any of theinterior spaces of the apparatus and thus preclude blockage of thepiston action so far described.

It will readily be seen that the movement of parts just described willnecessarily force into tubulation segment 1260 the body of liquidsolvent 130 shown in FIG. 1 as being enclosed by the diaphragm 83.Moreover, since tubulation 126 is now closed at its left hand end (seeFIG. 2) this liquid will necessarily be projected into the manifold 17and thence through the nozzle and the orifice 15a. The resultingspraying action will continue until the stored liquid has been entirelyexpelled, or, in any event until the piston cover plate 84 reaches thelimiting abutment 160. In this way a metered quantity of cleansing fluidis projected onto the surface of the inking roller 20 whence it will indue course be removed (along with dissolved ink) by action of the wipingblade 25. Because in normal usage a succession of spraying and wipingcycles are ordinarily employed, it is contemplated that the fluidcontrol apparatus will be caused to perform its various operatingfunctions a number of times during any given cleaning operation althoughthis is not necessary for the useful application of the presentinvention. In any event, whether one or more spraying cycles is to beperformed, the present invention contemplates that any given cycle willbe terminated by de-energizing the solenoid coil 139, thus permittingthe tension spring 135 to return the twochambered valve cylinder 1 10bto the position which it occupies in FIG. 1. Under these circumstances,the valve ports 122 and 124 will again be opened, thus directlyinterconnecting the openings 99 and through the tubular connections and126. Concurrently, the opening 95 will be disconnected from thepressurized liquid source 10. Because of the last-mentionedcircumstance, the compression spring 150, acting within the pistoncylinder 52, will be effective to move that cylinder to the left, thuscompressing the diaphragm 56. By this operation the cleansing liquid bcontained within the diaphragm-enclosed space will, as a first result,be forced through the tubular connections 120, 126, and 126a and thencethrough the opening 99 into the chamber enclosed by the diaphragm 83 atthe right hand end of the control apparatus. Because, as has beenpreviously explained, this chamber is significantly larger than thecorresponding chamber enclosed by the diaphragm 56, the full expansionof diaphragm 83 (i.e. to the position shown in FIG. 1) will in effectdraw a vacuum in that chamber which can only be filled by the in-draftof air through the nozzle 15. This action will be effective, regardlessof the orientation of the nozzle, to draw back into the nozzle andthence into the conduit system any droplets or particles of solventwhich might otherwise tend to accumulate in the vicinity of the orificein a condition which could permit subsequent dripping onto criticalsurfaces of the printing equipment. While this drawing in of solvent isespecially useful in the case in which the nozzle has a downwardlydirected orientation, it is also useful regardless of the specificnozzle orientation which is employed. In some cases the nozzle orificemay be directed upwardly so that liquid collected on the lip of theorifice would have a natural tendency (i.e. under the influence ofgravity) to flow back into the nozzle. Even in such a case, however, thepresent invention is still useful in that the mere lessening of thevolume of liquid contained in by the tubular portions 126 and 126a whichis inherently accomplished by the invention will facilitate, by syphoneffect and otherwise, the withdrawal of excess fluid from the vicinityof the orifice.

The apparatus construction of FIGS. 1 and 2 has a special advantage inthat a single pressurized fluid (i.e. the cleansing solvent itself)serves both as the means for compressing the piston represented by thecylinder 52 and for supplying solvent to the spray nozzle manifold 17.It will be understood, however, that, if desired for any reason, aseparate source of energization of the piston cylinder 52 may beemployed, such, for example, as a valve-controlled stream of pressurizedair or other fluid medium. From this point of view, a primaryrequirement of the present invention is that the volume of the chamberrepresented by the fully expanded diaphragm 83 must be greater than thevolume of solvent introduced into the conduit system when the diaphragmis compressed. Where this condition is met, reexpansion of the diaphragmunder the influence of the compression spring will, provided there isunrestricted communication between the diaphragmenclosed chamber and thenozzle manifold (as illustrated, for example, in FIG. I), produce anegative pressure at the nozzle orifices, with the beneficial resultspreviously described. For the achievement of the last-mentioned result,it is, of course, not essential that the discrepancy between the sizesof the two collapsible chambers be as great as that illustrated in FIGS.1 and 2. Indeed, for particular purposes, and especially where low costis vital, one may employ for purposes of the invention, the rod-end andhead-end chambers of a typical double-acting piston cylinder in whichthe maximum rod-end volume is necessarily less than the maximum head-endvolume by virtue of the space deducted from the former by the body ofthe rod itself.

In the arrangement of FIGS. 1 and 2, the function of introducing intothe space enclosed by the diaphragm 83 a quantity of liquid whichincompletely fills that space is accomplished in the following way. Whenthe diaphragm 56 is fully expanded as shown in FIG. 2, it will ofnecessity be filled by a specific quantity of pressurized solvent which,as described above, is the cause of its expansion. Moreover, the volumeof liquid 13Gb so contained is, by virtue of the specified relationshipbetween the sizes of the two diaphragms 56 and 83, significantly lessthan the expanded volume of the space enclosed by the latter diaphragm.Accordingly, when the solenoid coil 139 is de-energized so that thevalve system is returned to the position shown in FIG. I, the action ofthe spring 150 will be to drive the measured quantity of solventinitially contained within the dia phragm 56 through the tubulations120, 126 and 126a and through the wall opening 99 into the relativelylarge chamber in the process of being formed by the expanded diaphragm83. Thus, the partially filled condition of this chamber represented inFIG. 1 will be restored, the quantity of liquid received in the chamberbeing metered" in accordance with the dimensions of the diaphragm 56.

With the arrangement just described the cycle of the spray projectionfollowed by recapture of residual solvent from the spray orifices can berepeated as many times as desired. Where a succession of spraying andwiping cycles is desired, this may be accomplished automaticaily by useof an appropriate timing mechanism. By way of illustration only, anexemplary timing mechanism is pictured diagrammatically in FIG. 3. Inthis Figure the terminals 140 of the solenoid coil 339 (FIG. 1] areshown as being connected to an eiectrical power source 180, theapplication of which is controlled by a switch 185. Closure of thisswitch initiates rotation of a low speed motor 190 which, in turn,rotates a con tact-bearing wheel 200. Electrically conductive members205 spaced around the periphery of this wheel serve intermittently tointerconnect conductors 210 and H5, thus cyclically energizing the coil139. Any desired timing of the on and off portions of the switchingcycle can be provided by appropriate spacing and dimensions of thecontacts 205 and/or the speed of rotation of the output shaft of themotor 190. The switch 185 may also be electronically controlled tointerlock the operation of the spraying mechanism with the apparatuswhich controls the rotation of the roller and the action of the wipingblade 25.

While the invention has been described by reference 6 such variations asfall within the true spirit and scope of the invention.

I claim:

1. In a press washer, a liquid dispensing system of the type whichincludes a source of liquid, an orifice through which such liquid is tobe projected, and a conduit system extending between said source andsaid orifice for establishing a liquid-bearing connection between themto convey washing liquid to the press parts to be washed comprising,

A. control apparatus to be interposed in the conduit system, suchapparatus comprising, 1. a first expansible and collapsible chamber foralternatively a. establishing flow of liquid from the source to theportion of the conduit system which connects with the orifice when saidchamber is collapsed, and

b. a multi-position valve in the conduit system for interrupting suchflow, and

2. a second expansible and collapsible smaller chamber inter-connectedto said first chamber to operate in opposite expanding or collapsingphase thereto, and being connected to the conduit system through saidvalve when said valve interrupts flow from said first chamber andeffective upon such interruption of flow to establish a negativepressure within the portion of the conduit system which connects withthe orifice, thereby to withdraw residual liquid from the orifice.

2. For use in a liquid dispensing system of the type which includes asource of liquid, an orifice through which such liquid is to beprojected, and a conduit system extending between said source and saidorifice for establishing a liquid-bearing connecting between then;

A. control apparatus to be interposed in the conduit system, suchapparatus comprising 1. means for establishing flow of liquid from saidsource to a portion of the conduit system which connects with theorifice and for subsequently interrupting such flow, such meansincluding a. an expansible and collapsible chamber,

b. means for introducing into the chamber in its expanded condition ametered volume of liquid less than the expanded volume of the chamber,

c. means for progressively collapsing the chamber and thereafterprogressively re-expanding it, and

d. means operative during the progressive expat.

sion and contraction of the chamber for maintaining the chamber indirect communication with the said portion of the conduit system whichconnects with the orifice, whereby during the progressive collapsing ofthe chamber liquid may be projected through the orifice and during theprogressive expansion of the charm ber residual liquid may be withdrawnf'om the orifice.

3. Control apparatus according to claim 2 in which the said means forprogressively collapsing the said chamber comprises:

A. a second expansible and collapsible chamber which in its expandingphase operates to coilapse the first such chamber; and

B. control means for admitting to the second chamber pressurized fluidfor expanding that chamber.

10 biased toward its non-collapsed condition and having aliquid-conveying connection with the said orifice, and

b. the smaller of the two chambers being normally biased toward itscollapsed condition,

c. said two chambers being so interconnected that expansion of thelarger chamber compresses the smaller chamber and vice versa, and

which may be introduced into the second chamber dur- 10 ing itsexpanding phase will be transferred as a metered liquid quantity intothe first chamber during the second chambers collapsing phase.

6. Control apparatus according to claim 5 which fur- 2. multi-positionvalve means to be interposed between said pressurized liquid source andsaid chambers, said valve means a. being efi'ective in a first positionthereof to perther includes multi-position valve means for altemativelyA. admitting liquid from said supply source to said second chamber forexpanding it while maintaining that chamber out of connection with saidfirst chamber, and

B. terminating admission of liquid to the second chamber to permit itscollapse while establishing connection between that chamber and thefirst chamber, whereby the liquid content of the second chamber istransferred to the first chamber.

7. For use in a liquid dispensing system of the type which includes asource of pressurized liquid, an orifice to which such liquid is to besupplied, and a conduit system extending between said source and saidorifice:

A. flow control apparatus to be interposed in the conduit system, suchapparatus comprising 1. an assembly of two separately constitutedcollapsible chambers, one of which is of significantly greater internalvolume than the other, a. the larger of the two chambers being normallymit delivery of pressurized liquid from the source to the smaller of thetwo chambers, thereby concurrently expanding that chamber and collapsingthe larger chamber so as to impel toward the orifice any liquidcontained in the larger chamber, and

b. being effective in a second position thereof to interconnect saidfirst and second chambers while isolating both chambers from saidpressurizled fluid source, whereby the concurrent expansion of thelarger chamber and contraction of the smaller chamber which occurs underthe influence of their normal biases i. transfers from the smaller tothe larger of the chambers a metered amount of liquid corresponding tothe decrease in volune of the smaller chamber, and

ii. produces in the larger chamber a net pressure decrease effective towithdraw residual liquid from the orifice connected to it.

i i I I i

1. In a press washer, a liquid dispensing system of the type whichincludes a source of liquid, an orifice through which such liquid is tobe projected, and a conduit system extending between said source andsaid orifice for establishing a liquid-bearing connection between themto convey washing liquid to the press parts to be washed comprising, A.control apparatus to be interposed in the conduit system, such apparatuscomprising,
 1. a first expansible and collapsible chamber foralternatively a. establishing flow of liquid from the source to theportion of the conduit system which connects with the orifice when saidchamber is collapsed, and b. a multi-position valve in the conduitsystem for interrupting such flow, and
 2. a second expansible andcollapsible smaller chamber interconnected to said first chamber tooperate in opposite expanding or collapsing phase thereto, and beingconnected to the conduit system through said valve when said valveinterrupts flow from said first chamber and effective upon suchinterruption of flow to establish a negative pressure within the portionof the conduit system which connects with the orifice, thereby towithdraw residual liquid from the orifice.
 2. multi-position valve meansto be interposed between said pressurized liquid source and saidchambers, said valve means a. being effective in a first positionthereof to permit delivery of pressurized liquid from the source to thesmaller of the two chambers, thereby concurrently expanding that chamberand collapsing the larger chamber so as to impel toward the orifice anyliquid contained in the larger chamber, and b. being effective in asecond position thereof to interconnect said first and second chamberswhile isolating both chambers from said pressurized fluid source,whereby the concurrent expansion of the larger chamber and contractionof the smaller chamber which occurs under the influence of their normalbiases i. transfers from the smaller to the larger of the chambers ametered amount of liquid corresponding to the decrease in volune of thesmaller chamber, and ii. produces in the larger chamber a net pressuredecrease effective to withdraw residual liquid from the orificeconnected to it.
 2. For use in a liquid dispensing system of the typewhich includes a source of liquid, an orifice through which such liquidis to be projected, and a conduit system extending between said sourceand said orifice for establishing a liquid-bearing connecting betweenthem, A. control apparatus to be interposed in the conduit system, suchapparatus comprising
 2. a second expansible and collapsible smallerchamber inter-connected to said first chamber to operate in oppositeexpanding or collapsing phase thereto, and being connected to theconduit system through said valve when said valve interrupts flow fromsaid first chamber and effective upon such interruption of flow toestablish a negative pressure within the portion of the conduit systemwhich connects with the orifice, thereby to withdraw residual liquidfrom the orifice.
 3. Control apparatus according to claim 2 in which thesaid means for progressively collapsing the said chamber comprises: A. asecond expansible and collapsible chamber which in its expanding phaseoperates to collapse the first such chamber; and B. control means foradmitting to the second chamber pressurized fluid for expanding thatchamber.
 4. Control apparatus according to claim 3 in which the firstchamber in its expanded condition has an enclosed volume significantlygreater than the enclosed volume of the second chamber in its expandedcondition.
 5. Control apparatus according to claim 4 which furtherincludes means effective during the collapsing phase of the secondchamber to connect that chamber with the interior of the first chamber,whereby liquid which may be introduced into the second chamber duringits expanding phase will be transferred as a metered liquid quantityinto the first chamber during the second chamber''s collapsing phase. 6.Control apparatus according to claim 5 which further includesmulti-position valve means for alternatively A. admitting liquid fromsaid supply source to said second chamber for expanding it whilemaintaining that chamber out of connection with said first chamber; andB. terminating admission of liquid to the second chamber to permit itscollapse while establishing connection between that chamber and thefirst chamber, whereby the liquid content of the second chamber istransferred to the first chamber.
 7. For use in a liquid dispensingsystem of the type which includes a source of pressurized liquid, anorifice to which such liquid is to be supplied, and a conduit systemextending between said source and said orifice: A. flow controlapparatus to be interposed in the conduit system, such apparatuscomprising